Analysis of carnitine biosynthesis metabolites in urine by HPLC-electrospray tandem mass spectrometry.

Background: We developed a method to determine the urinary concentrations of metabolites in the synthetic pathway for carnitine from N(6)-trimethyllysine and applied this method to determine their excretion in control individuals. In addition, we investigated whether newborns are capable of carnitine synthesis from deuterium-labeled N(6)-trimethyllysine.

Methods: Urine samples were first derivatized with methyl chloroformate.